Apparatus for compressing and packing molding sand



March 1970 H. GROLLA 3,503,436

APPARATUS FOR COMPRESSING AND PACKING MOLDING SAND 'Filed Dec. 28, 1967 2 Sheets-Sheet 1 Inventor H6 r70 8 Ft Grofk March 31, 1970 H. GR'QLLA 3,503,436

' APPARATUS FOR COMPRESSING AND PACKING MOLDING SAND Filed Dec. 28, 1967 2 Sheets-Sheet 2 Inventor H e'kEe/i (1 r0 2&2

United States Patent 3,503,436 APPARATUS FOR COMPRESSING AND PACKING MOLDING SAND Herbert Grolla, Laasphe im Westphalia, Germany, as-

signor to Firma Heinrich Wagner Maschinenfabrik, Laasphe im Westphalia, Germany Filed Dec. 28, 1967, Ser. No. 694,329

Claims priority application Germany, Dec. 28, 1966,

W 43,079 Int. Cl. B22c /00 US. Cl. 164-172 7 Claims ABSTRACT OF THE DISCLOSURE An apparatus for compressing and packing casting and moulding sand in a form by means of a plurality of auto matic tampers, operable together and guided in frame members.

This invention relates to an apparatus for compressing and packing casting or moulding sand in connection with the production of cast forms. The installation includes a plurality of small compacting or compressing elements which together form an elongated and transverse field, particularly in connection with the automatic production of sand casting molds there exists the problem to provide as nearly as possible a uniform packing of the sand. In automatic tampers this presents difficulties to produce a uniform packing since a regulated connection on the tamping force, as compared by hand devices or molds, will be suppressed.

The present invention has for an object to provide a tamping device in which a single drive for the tamping elements is not necessary.

According to the invention, the field for the tamping elements will cover the entire upper surface of the mold or box to be tamped and that the tamping elements in their tamping operation are formed as tampers functioning as single elements due to their own weights and guided in guide frames in their up and down movements. If in such tamping device, the frame with its guided tampers moves downwardly, then the individual tampers will fall on the upper surface of the sand to be compacted, whereby in addition to the weight, the tampers due to their dynamic energy will fall on the sand by their own falling acceleration. The necessary tamping can thus be attained with one or more tamping blows.

Even for a large number of single tampers it is sufiicient to provide a single driving arrangement, whereby the automatically operating tamping device can be struc turally simple and thus can be inexpensively produced. Obviously one can use a plurality of groups of tampers to tamp large forms of which each could have its own drive. Also in such arrangements the advantage is attained that not every single tamper must have its drive.

Advantageously each single tamper may have its quadrilateral, preferably square, cross-sectional form. With such tampers one will achieve the simple possibility to attain uniform field of action. Also other forms of tampers can be used such as hexagon shapes to provide a cooperative pattern for the tampers.

A compresed air drive can be used to raise and lower the frames for the tampers, whereby the control for the entry and exit of air can be controlled by slide valves for the piston operators. Such mechanical controls can be designed without any ditficulties.

The guide frames can be supported by suitable suspension beams. In this case the drive for raising and lowering is carried out between the guide frames and the beams on which the compressed air pistons are arranged whereas the air pressure cylinders are secured on the machine frames. This complete structure will form a compact construction.

Each single tamper preferably has a lower tamping part, a middle preferable cylindrical guide part and an upper guide part forming a tamping weight as a raised head part. By such structures, the tampers can be suitably provided with sufficient space between tampers and at the same time providing a good guiding arrangement for the tamper weight with desired cooperating proximity of the individual tampers.

The non-rotary and fixed individual tampers can be easily arranged so that the tampers may be provided with fiat sides close to or actually contacting each other. The guide means can however be so formed that the head parts are square in cross-section in contact or spaced from each other. The tampers may have means so that the head parts alone are provided with means to prevent rotation.

The tamping mechanism according to this invention has the advantage that it can be used for the continuous production of casting forms in sand molds and the ap paratus can be operated step-wise and provided with a sand storage funnel for feeding sand to the mold boxes or frames. Further objects will be apparent from the following description when considered in connection with the accompanying drawing in which:

gIGURE 1 is a side view of the tamping installation an FIGURE 2 is a front view of the installation in the direction of the arrow II of FIGURE 1.

The entire sand packing machine or installation is indicated by reference No. 1, and this structure is provided above a conveying device 2, carrying thereon the casting boxes or casings 3. The structure consists essentially of a battery 4, of stamping or tamping devices which are held together in a guide frame 5 and a driving mechanism 6.

The battery 4 of tamping elements consists of a plurality of individual tamping members 7 of which each is provided with a head part 8, a guide portion 9 and a lower tamping part or element 10. The horizontal crosssection of the head parts 8 and the tamping parts 10 are quadrilateral in cross-section and they are of the same size as to the head and tamping parts. The head and tamping parts have the interconnecting parts which are guide members 9 and they have a circular cross-section and are slidably guided in a guide frame 5 of the guide member as clearly illustrated on the drawing. The intervals between the sliding guides in the guide frame 5 and the cross'sectional measurements of the head and tail parts are so provided in relation to each other that there remains only a small width at between the vertical side surfaces of the four edges. The distance d will be provided in its greater dimension of approximately 1 mm. From the drawing itself it can be observed that the tamping part 10 and the head part 8 are so inter-related and arranged that they will not rotate even though the intermediate guide member 9 has a round cross-sectional configuration.

Guide frame 5 is suspended above a carrying element 11 and 11' from a T-shaped element on a beam of I- shaped cross-section.

In order to provide for a sufficient lateral stability, the carrier or suspending members 11 and 11 are mounted to the beam 12 by means of triangular metal members 13 and 13.

Between the tamping battery 4 and the beam 12, there is provided the driving device or structure 6. This latter includes a structure which in connection with casting machines is well known, as driven by compressed air. On a part 14 of the machine frame there is secured a compressed air cylinder 15 in which there is slidably arranged a hollow piston 16. The hollow space for the cylinder is as to its greater part, filled with a bottom cylinder cover 17 mounted on a filling member 18. The compressed air will flow through the line 19 and will be distributed in the space between the member 18 and the inner hollow chamber of the piston 16. Thus, by means of this structure the piston can be raised and a particular stroke of the piston, the ring channel 20 in the piston 16 will be directed outwardly in communication with the ring channel 21. The further upward movement will be accompanied by a comparative compression of the air under pressure. When the lower edge of the piston projects beyond the ring channel 22 of the piston, then the compressed air will be diverted outwardly and the piston will fall, accelerated by its own weight. Such drive procedures as mentioned in the foregoing are known in casting machines.

The lowering movement of the tamping device will be limited due to safety reasons by the beam contacting the buffer devices 34 and 34' mounted on the machine frame.

The structure shown on the drawing, in addition to the filling device, also has a filling trough or funnel having its mouth 24 spaced somewhat above the molding box or case 3. The feeding trough is mounted directly adjacent the tamping installation and is separated therefrom by means of a sheet metal member 25 (FIG. 1), which is in communication with the lateral sheet metal shields 32 and 32 as well as with the rear sheet metal member '25 so that thus there is provided a suitable space for the flow of the sand and even when compressed, the sand will not be spilled out from the apparatus to any extent. At the lower end of the sheet metal member 26 there is provided a scraper Which after the compressed uneven top surface of the casting box, will tend to smooth out the moulding material. Any sand which has been loosened by this structure will be directed into an electrically driven transporting conveyor 28 which latter has a spiral or screw form.

The casting boxes 3 are known in themselves as mounted on modeling plates 29 on which the patterns 30 are placed.

The compressing and tamping structure according to the invention operates as follows:

The casting boxes 3 will be moved step by step in the direction of the arrow 31 in FIG. 1, and actually extending across the width of the casting boxes. Thus, the casting "boxes will be moved one by one under the opening 24 of the filling devices 23, and in the movement of the form boxes, the latter will be filled with the moulding sand 32. After filling, the filled boxes or moulds will be directed under the compacting device 1. During this movement, the beam 12 and therewith also the guide frame 5 will be elevated so that the individual tamping member 7 will be prevented from sinking further, due to the head parts 8, and they are lifted so far that any overfilled box can be moved under the tamping members. Now the beam 12 and therewith the guide frame 5 will be entirely free so that the individual tamping members 7 can fall or strike the sand so that the latter will be compressed by tamping action. If necessary, a plurality of tamping strokes can be carried out and the small side of each casting box will be closed over the sheet metal members 32 and 32' which will thus prevent any sand from falling out of the casting boxes.

I claim:

1. An apparatus for compressing casting and molding sand in forms comprising a frame, a guide frame vertically mounted and guided in the first-mentioned frame, a plurality of adjacent tamping members slidably mounted in the guide frame and capable of vertical movement relative to and in the guide frame, said tamping members each having upper retaining means adapted to normally rest on said guide frame and for at least a lower part thereof as to its length a prismatic form having a crosssection so that said plurality of adjacent tamping members will have approximately no spaces between the prismatic forms to thereby prevent rotary motion of the tamping members relative to the guide frame drive means to vertically raise said guide frame and tamping members, and means adapted to effect release of said drive means to enable said guide frame and tamping members to fall, said plurality of adjacent tamping members forming a battery of longitudinal and lateral rows of members.

2. An apparatus according to claim 1, in which at least two buffer devices are mounted on the guide frame to cooperate with the first-mentioned frame.

3. An apparatus according to claim 1, in which said drive means comprises a compressed air system connected to said first-mentioned frame to operate the raising and lowering of the guide frame and tampin members.

4. An apparatus according to claim 1, in which said drive means comprises a compressed air system connected to said first-mentioned frame to operate the raising and lowering of the guide frame and tamping members, and having a piston and cylinder with control means in the cylinder in the form of a slide valve.

5. An apparatus according to claim 1, in which said drive means comprises a compressed air system mounted between said first-mentioned frame and said guide frame in which damping members are mounted on and between said first-mentioned frame and said guide frame to take up the shock of operation of the tamping action.

6. An apparatus according to claim 1, in which each tamping member has head and base portions of approximately rectangular cross-section and a round inter-connecting portion between the rectangular portions.

7. An apparatus according to claim 1, in which a trough-like member is mounted adjacent said first-mentioned frame to store and feed sand to said frames.

References Cited UNITED STATES PATENTS ROBERT D. BALDWIN, Primary Examiner US. 01. X.R. 

